[MDEV-16134] Wrong I_S.COLUMNS.CHARACTER_XXX_LENGTH value for compressed columns Created: 2018-05-10  Updated: 2018-05-10  Resolved: 2018-05-10

Status: Closed
Project: MariaDB Server
Component/s: Data types
Affects Version/s: 10.3
Fix Version/s: 10.3.7

Type: Bug Priority: Major
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-15592 Column COMPRESSED should select a 'hi... Closed

 Description   

This script queries I_S for a latin1 compressed varchar column:

CREATE OR REPLACE TABLE t1 (a VARCHAR(10) CHARACTER SET latin1 COMPRESSED);
 
SELECT
 
  CHARACTER_MAXIMUM_LENGTH, CHARACTER_OCTET_LENGTH
 
FROM
 
  INFORMATION_SCHEMA.COLUMNS
 
WHERE
 
  TABLE_SCHEMA='test' AND TABLE_NAME='t1' AND COLUMN_NAME='a';


+--------------------------+------------------------+
 
| CHARACTER_MAXIMUM_LENGTH | CHARACTER_OCTET_LENGTH |
 
+--------------------------+------------------------+
 
|                       11 |                     11 |
 
+--------------------------+------------------------+

11 looks wrong. The expected value would be 10 for both columns.

Now trying an utf8 column:

CREATE OR REPLACE TABLE t1 (a VARCHAR(10) CHARACTER SET utf8 COMPRESSED);
 
SELECT
 
  CHARACTER_MAXIMUM_LENGTH, CHARACTER_OCTET_LENGTH
 
FROM
 
  INFORMATION_SCHEMA.COLUMNS
 
WHERE
 
  TABLE_SCHEMA='test' AND TABLE_NAME='t1' AND COLUMN_NAME='a';


+--------------------------+------------------------+
 
| CHARACTER_MAXIMUM_LENGTH | CHARACTER_OCTET_LENGTH |
 
+--------------------------+------------------------+
 
|                       10 |                     31 |
 
+--------------------------+------------------------+

The value for CHARACTER_OCTET_LENGTH is wrong. The expected result is 30.

 Comments   
Comment by Sergey Vojtovich [ 2018-05-10 ]

Ok to push.

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